Semiconductor wafer holder and electroplating system for plating a semiconductor wafer

ABSTRACT

A semiconductor wafer holder including first and second holding members between which a semiconductor wafer is held. The second holding member includes a second conductive element placed in contact with a first conductive element of the first holding member and the semiconductor wafer. A ring clamp is used to press the second holding member against the first holding member for holding of the semiconductor wafer.

[0001] This is a continuation application of Ser. No. 09/463,698, filedJan. 31, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The present invention relates to a semiconductor wafer holder andan electroplating system for plating a semiconductor wafer. Thesemiconductor wafer holder is designed to hold a semiconductor waferduring electrolytic plating.

[0004] 2. Description of Related Art

[0005] A conventional semiconductor wafer holder holds a semiconductorwafer so that a conductive pin is placed in contact with a conductivelayer of the semiconductor wafer during electrolytic plating. The waferholder together with the semiconductor wafer is immersed in anelectrolyte bath within which an electrolytic solution is contained.Electrical current is supplied to the semiconductor wafer through theelectrolytic solution and the conductive pin for electrolytic plating ofthe semiconductor wafer.

[0006] With such an arrangement, however, it is not easy to mount thesemiconductor wafer to the holder. Also, the conductive pin can not bereliably contacted with the conductive layer of the semiconductor wafer.

[0007] In view of the foregoing, it is a first object of the presentinvention to provide a semiconductor wafer holder which enables readymounting of a semiconductor wafer and reliable application of electricalcurrent to a conductive layer of the semiconductor wafer.

[0008] The prior art semiconductor wafer holder includes a packing forsealing of the conductive pin. The packing extends between thesemiconductor wafer and a holding element by which the semiconductorwafer is held. A plurality of bolts are tightened to clamp the packing,whereby uniform pressure is exerted on the packing to seal theconductive pin.

[0009] Such an approach is, however, cumbersome. It is also difficult toapply uniform torque to each bolt. Uneven application of torque maycause the electrolytic solution to reach the conductive pin.

[0010] In view of the foregoing, it is a second object of the presentinvention to provide a semiconductor wafer holder which facilitatesclamping of a packing and enables uniform application of a clampingforce to the perimeter edge of the packing.

SUMMARY OF THE INVENTION

[0011] According to a first aspect of the present invention, there isprovided a semiconductor wafer holder comprising a first holding member,and a second holding member with a packing adapted to cooperate with thefirst holding member to sandwich a semiconductor wafer. Thesemiconductor wafer is exposed through inside of the packing.

[0012] The first holding member includes a first conductive elementadapted for electrical connection with an external electrode.

[0013] The second holding member includes a second conductive elementadapted for contact with the first conductive element of the firstholding member and a conductive layer of the semiconductor wafer andsealed by the packing.

[0014] In the first aspect of the invention, it is preferable that thepacking has an annular shape, and the first conductive element isarranged adjacent to the outer periphery of the semiconductor wafer heldbetween the first and second holding members.

[0015] It is also preferable that the packing has an inverted U-shapedsection, with opposite end projections placed in contact with the firstholding member and the semiconductor wafer, respectively, and thepacking includes a hole defined between the end projections, the secondconductive element being received in the hole.

[0016] The second conductive element preferably has an inverted U-shapedsection, with two end projections configured to bridge between the firstconductive element and the conductive layer of the semiconductor wafer.A resilient member is preferably used to mount the second conductiveelement within the hole.

[0017] In another embodiment, a semiconductor wafer holder comprises afirst holding member including a first conductive element, and a secondholding member including a second conductive element, wherein the firstholding member and the second holding member are operatively associatedwith each other so as to releasably hold a semiconductor wafertherebetween, and the first conductive element and the second conductiveelement are maintained out of contact with a plating liquid, and whereinthe second conductive element of the second holding member is held incontact with the first conductive element of the first holding memberand the semiconductor wafer when the semiconductor wafer is sandwichedbetween the first holding member and the second holding member.

[0018] According to a second aspect of the present invention, there isprovided a semiconductor wafer holder comprising a plate-like firstholding member, an annular second holding member with a packing mountedthereon, a ring clamp operable to press the second holding memberagainst the first holding member so as to hold a semiconductor wafertherebetween, and a conductive member placed in contact with theconductive layer of the semiconductor wafer and sealed by the packing.

[0019] In another embodiment, a semiconductor wafer holder comprises afirst holding member in the form of a plate, an annular second holdingmember including a packing mounted thereon, and a ring clamp operable topress the second holding member against the first holding member so asto hold a semiconductor wafer therebetween.

[0020] The first holding member includes a first conductive elementarranged adjacent to the outer periphery of the semiconductor wafer heldbetween the first and second holding member.

[0021] Also, the packing of the second holding member includes a secondconductive element placed in contact with the first conductive elementand the conductive layer of the semiconductor wafer held between thefirst and second holding members and sealed by the packing.

[0022] It is preferable that the ring clamp includes a plurality ofprotrusions formed on its outer periphery and arranged at givenintervals, and the first holding member includes a plurality of pawls ofan inverted L-shape. The plurality of protrusions are slid below theplurality of pawls to thereby clamp the first and second holding memberstogether when the ring clamp is rotated by a given angle.

[0023] It is also preferable that the first holding member and thesecond holding member are connected by and pivoted about a hingemechanism.

[0024] It is further preferable that the second holding member and thering clamp are connected by a ring retainer and capable of rotation onthe second holding member by a given angle.

[0025] In another embodiment, a semiconductor wafer holder comprises afirst holding member, a second holding member and a clamping ringmovable between a clamp position and an open position and including alocking member.

[0026] The first and second holding members are cooperative toreleasably hold a semiconductor wafer therebetween.

[0027] One of the first and second holding members includes a lockableportion to be releasably engaged with the locking member.

[0028] The locking member is engaged with the lockable portion so as tolock the first and second holding members together when the clampingring is held in the clamp position.

[0029] Also, the first holding member and the second holding member areunlocked when the clamping ring is held in the open position, wherebythe semiconductor wafer can be loaded between and unloaded from thefirst and second holding members.

[0030] According to a third aspect of the present invention, there isprovided an electroplating system for plating a semiconductor wafercomprising a semiconductor wafer holder as set forth in any one of theforegoing embodiments.

[0031] In the third aspect of the invention, an electroplating systemfor plating a semiconductor wafer, comprises a loading/unloading stationfor transferring the semiconductor wafer from a wafer cassette to asemiconductor wafer holder and vice versa, and

[0032] a plating bath station including a plating bath within which aplating liquid is contained, the semiconductor wafer holder with thesemiconductor wafer mounted therein being immersed in the plating liquidwhereby the semiconductor wafer is plated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a perspective view showing the outer appearance of asemiconductor wafer holder according to one embodiment of the presentinvention;

[0034]FIG. 2 is a sectional view illustrating the positionalrelationship between a first conductive element and a packing when asecond holding member is placed on a first holding member of thesemiconductor wafer holder shown in FIG. 1;

[0035]FIG. 3A is a front view of the semiconductor wafer holder;

[0036]FIG. 3B is a side view of the semiconductor wafer holder;

[0037]FIG. 4 is a schematic view of an electroplating system accordingto another embodiment of the present invention;

[0038]FIG. 5 is a sectional view of another embodiment of thesemiconductor wafer holder, illustrating the positional relationshipbetween a first conductive element and a packing when a second holdingmember is placed on a first holding member of the semiconductor waferholder;

[0039]FIG. 6 is a sectional view of one form of a hinge mechanism;

[0040]FIG. 7A is a perspective view showing the outer appearance of asemiconductor wafer holder according to another embodiment of thepresent invention, with a first holding member in its open position;

[0041]FIG. 7B is an enlarged view of a portion B encircled in FIG. 7A;

[0042]FIG. 8 is a perspective view showing the outer appearance of thesemiconductor wafer holder shown in FIG. 7A, with the first holdingmember in its closed position;

[0043]FIG. 9 is a sectional view taken along the line C-C of FIG. 8;

[0044]FIG. 10 is a sectional view showing the positional relationshipbetween the first conductive element and a semiconductor wafer duringclamping;

[0045]FIG. 11 is a sectional view showing the positional relationshipbetween a conductive member and a semiconductor wafer during clamping;

[0046]FIG. 12 is a side view of a electroplating system for plating asemiconductor wafer, made according to a different embodiment of thepresent invention;

[0047]FIG. 13 is a plan view of the electroplating system; FIG. 14A is asectional view of one form of a holder clamp; and

[0048]FIG. 14B is a sectional view of one form of a semiconductor waferholder.

DETAILED DESCRIPTION OF THE INVENTION

[0049] The present invention will now be described with reference to thedrawings. FIGS. 1, 2, 3A and 3B show a semiconductor wafer holderaccording to one embodiment of the present invention. FIGS. 7A, 7B, 8, 9and 10 show another embodiment of the semiconductor wafer holderaccording to the present invention.

[0050]FIG. 1 is a perspective view showing the outer appearance of asemiconductor wafer holder according to one embodiment of the presentinvention. As shown, a holder 10 includes a first, plate-like holdingmember 11 made of an electrically insulative material (such as syntheticresin), and a second, plate-like holding member 12 made of anelectrically insulative material (such as synthetic resin) and providedwith an annular seal or packing 13. The second holding member 12 isconnected to the first holding member 11 by means of a hinge mechanism14. A handle 15 is formed at one end of the first holding member 11remote from the hinge mechanism 14.

[0051] A recess is formed in the upper surface of the first holdingmember 11 to receive a semiconductor wafer 16. The recess issubstantially identical in shape to the semiconductor wafer 16. Aplurality of first conductive elements 17 (four conductive elements areshown) are arranged in the outer periphery of the recess in acircumferentially equally spaced relationship. The top surface of eachof the first conductive elements 17 is substantially coincident with thetop surface of the first holding member 11. The second holding member 12has a central opening 12 a which has an inner diameter slightly smallerthan the diameter of the semiconductor wafer 16. An annular packing 13is placed on the second holding member 12 and secured to the perimeteredge of the opening 12 a.

[0052] The packing 13 has an inverted U-shaped section, with oppositeend projections 13 a, 13 b. The packing 13 has a width so that the endprojections 13 a, 13 b are contacted with the upper surface of the firstholding member 11 and the surface of the semiconductor wafer 16,respectively. The end of the packing 13 projects from the upper surfaceof the second holding member 12 by a predetermined distance. A pluralityof holes 13 c (four are shown) are formed in the packing 13 to receive aplurality of corresponding second conductive elements 18 which willlater be described. The holes 13 c are arranged between the endprojections 13 a, 13 b and spaced at given intervals.

[0053] With this arrangement, the second holding member 12 is placed onthe first holding member 11 through the hinge mechanism 14 after thesemiconductor wafer 16 is inserted within the recess of the firstholding member 11. At this time, the end projections 13 a, 13 b of thepacking 13 are brought into contact with the upper surface of the firstholding member 11 and the surface of the semiconductor wafer 16,respectively. The first holding member 11 cooperates with the packing 13to sandwich the perimeter edge of the semiconductor wafer 16. Thesurface of the semiconductor wafer 16 is exposed through the opening 12a of the second holding member 12.

[0054]FIG. 2 illustrates the positional relationship between the firstconductive elements 17 and the packing 13 when the second holding member13 is placed on the first holding member 11. As shown, the endprojections 13 a, 13 b of the packing 13 are placed in contact with theupper surface of the first holding member 11 and the upper surface ofthe semiconductor wafer 16, respectively. The second conductive elements18 have a cylindrical configuration. A slot 18 a is formed in one end ofthe second conductive element 18 to provide two end projections 18 b, 18c. The second conductive element 18 thus has an inverted U-shapedsection. The second conductive element 18 is attached to the secondholding member 12 by a spring 19 so that the end projections 18 b, 18 care in contact with a conductive layer on the top of the semiconductorwafer 16 and the upper surface of the first conductive element 17,respectively. A conductive member 20 extends through the first holdingmember 11. The first conductive element 17 is connected through theconductive member 20 to an external electrode (not shown).

[0055]FIGS. 3A and 3B show the state in which the second holding member12 is placed on the first holding member 11. FIGS. 3A and 3B are frontand side views of the wafer holder 10. As shown, one end of the firstholding member 11, which includes the handle 15, and one end of thesecond holding member 12 remote from the hinge mechanism 14 are securedby a clamp 21. By this arrangement, the semiconductor wafer 16 is heldbetween the first holding member 11 and the packing 13, and theconductive member 20 is reliably electrically connected to theconductive layer of the semiconductor wafer 16 through the firstconductive elements 17 and the second conductive elements 18. Asmentioned earlier, the conductive layer of the semiconductor wafer 16 isconnected to the external electrode.

[0056]FIG. 4 is a schematic view of an electroplating system with thesemiconductor wafer holder 10. In this figure, 30 denotes a plating bathwithin which an anode 31 and the semiconductor wafer holder 10 areplaced. A pump 35 is used to send an electrolytic solution to theplating bath 30 through a filter 32. Part of the electrolytic solutionwhich overflows from the plating bath 30 is returned to the pump forcirculation through the system. A direct current source 34 has apositive terminal connected to the anode and a negative terminalconnected to an external electrode 33. The semiconductor wafer is platedupon supply of direct current from the direct current source 34.

[0057] As mentioned earlier, the wafer holder includes two separateconductors (the first and second conductive elements 17, 18) mounted tothe first and second holding members 11, 12, respectively. Thesemiconductor wafer 16 is conveniently contained in the recess of thefirst holding member 11, and the conductive member 20 extends throughthe first holding member 11. The second conductive elements 18 as aconductive pin are mounted to the other, second holding member 12. Thisarrangement facilitates mounting of the semiconductor wafer 16. Thesecond conductive elements 18 have an inverted U-shaped section and aremounted to the second holding member 12 by means of the spring 19. Thetwo end projections of each of the second conductive elements 18 are incontact with the first conductive elements 17 and the conductive layerof the semiconductor wafer 16, respectively. This arrangement enablesreliable supply of current to the conductive layer if, for example, thetop of the semiconductor wafer 16 is not coincident with the top of thefirst conductive element 17 as shown in FIG. 5.

[0058]FIG. 6 shows one form of the hinge mechanism 14. The hingemechanism 14 includes a hinge body 14 a secured to the first holdingmember 11 and a hinge pin 14 b secured to the second holding member 12for engagement with the hinge body 14 a.

[0059] Illustratively, the springs 19 are used to mount the secondconductive elements 18 to the second holding member. However, any otherresilient materials may, alternatively, be employed.

[0060]FIGS. 7A, 7B and 8 are perspective views showing the outerappearance of a semiconductor wafer holder according to the presentinvention. As shown, a wafer holder 110 includes a plate-like firstholding member 111, a second holding member 112 to which an annular sealor packing 113 is mounted, and a ring clamp 114.

[0061] The first holding member 111 is made of an electricallyinsulative material (such as synthetic resin). The first holding member111 is in the form of a rectangular plate and has a central recesswithin which a semiconductor wafer 116 is placed. A plurality of firstconductive elements 117 (eight conductive elements are shown) arelocated adjacent to the perimeter edge of the central recess andarranged in a circumferentially equally spaced relationship. The top ofthe first conductive elements 117 is substantially coincident with thatof the first holding member 111. A plurality of pawls 120 (eight areshown) are arranged outside of the first conductive elements 117 andspaced at equal intervals. The pawls 120 have an inverted L-shape.

[0062] The second holding member 112 is made of an electricallyinsulative material (such as synthetic resin). As shown, the secondholding member 112 includes a ring 112 a and a straight arm 112 bintegrally formed with the ring 112 a. The packing 113 has an invertedU-shape and is made of an electrically insulative material such asrubber and other elastic materials. As shown, the packing 113 isattached to one side of the ring 112 a of the second holding member 112.A plurality of holes 113 a (eight holes are shown) are formed, at equalintervals, in the packing 113 and located between its opposite endprojections. Inserted within the holes 113 a are a plurality of secondconductive elements 118 which will later be described (see FIG. 7B).

[0063] A plurality of protrusions 114 b (eight protrusions are shown)extend from the outer periphery of the ring clamp 114 and are arrangedat given intervals. A plurality of guide slots 114 a (four slots areshown) are formed in the upper side of the ring clamp 114 and arrangedat given intervals. A plurality of ring retainers 119 are formed on thetop surface of the ring 112 a of the second holding member 112 andextend through the guide slots 114 a. The ring clamp 114 is capable ofrotation (sliding movement) on the top surface of the second holdingmember 112. Specifically, the ring clamp 114 is rotated on the ring 112a by a given angle while being guided by the ring retainers (threeretainers are shown). The arm 112 b of the second holding member 112 hasone end pivotally connected to one side of the first holding member 111by means of a hinge mechanism 115.

[0064] With the wafer holder 110 thus constructed, the second holdingmember 112 is pivoted through the hinge mechanism 115 and then, placedon the first holding member 111. The ring 114 is pushed or rotated inthe direction of arrow A. This rotation causes the protrusions 114 b toslide below the pawls 120. As a result, the first holding member 111 andthe second holding member 112 are clamped together.

[0065] With the first holding member 111 and the second holding member112 clamped together, the end projection 113 b is contacted with theperimeter edge of the semiconductor wafer held within the recess of thefirst holding member 111, as shown in FIG. 9. The other end projection113 c is in contact with the first holding member 111.

[0066] The second conductive element 118 is made of an electricallyinsulative material (such as synthetic resin) and takes a cylindricalshape. A slot 118 a is formed in one end of the second conductiveelement 118 so that the second conductive element 118 has an invertedU-shape. The other, rear end of the second conductive element 118 isattached to the packing 113 or the second holding member 112 through aspring 121. With the second holding member 112 placed on the firstholding member 111, the end projection 118 b of the second conductiveelement 118 is in contact with the conductive layer on the semiconductorwafer 116, whereas the end projection 118 c is in contact with the firstconductive element 117, as shown in FIG. 10. A conductive member 122extends through the first holding member 111. The first conductiveelement 117 is connected to the conductive member 122 which is, in turn,connected to an external electrode, not shown.

[0067] In this embodiment, the protrusions 114 b are arranged, at givenintervals, on the outer periphery of the ring clamp 114. Upon rotationof the ring clamp 114, the protrusions 114 b are slidably moved belowthe pawls 120 so as to clamp the first holding member 111 and the secondholding member 112 together. This arrangement enables uniformapplication of pressure on the packing 113 and thus, provides a betterseal. It will be noted that the first conductive element 117 isconnected to the conductive member 122 which is, in turn, connected toan external electrode, not shown.

[0068] In the embodiment shown in FIG. 10, the end projection 118 b ofthe second conductive element 118 is contacted with the conductive layeron the semiconductor wafer 116, and the other end projection 118 c iscontacted with the first conductive element 117 when the second holdingmember 112 is superposed on the first holding member 111.

[0069] Alternatively, the first conductive element 117 may be omitted.As shown in FIG. 11, a conductive member 123 may be contacted with theconductive layer of the semiconductor wafer 116. The conductive member122 may also extend through the second holding member 112 and may beconnected to the conductive member 123 through the spring 121.

[0070] The wafer holder 110 shown in FIGS. 7A, 7B, 8 and 9 may be usedwith the electroplating system shown in FIG. 4.

[0071] The semiconductor wafer holder of the present invention issuitable for use in the electroplating system.

[0072] In a conventional “dip-type” plating system, a semiconductorwafer must manually be mounted to a carrier or holder. However, a largersemiconductor wafer is difficult to mount by hand. There thus exists aneed for a fully automated electroplating system to plate an 8-inchsemiconductor wafer. In such a system, a start button is pressed tothereby automatically plate a wafer while a wafer cassette within whichthe wafer is mounted is placed in a give position. The wafer is,thereafter, loaded back into the wafer cassette.

[0073]FIGS. 12 and 13 show one form of a electroplating system forplating a semiconductor wafer. This system is suitable for use with thewafer holder of the present invention. In FIG. 12, an electroplatingsystem 200 includes a wafer inlet 201 through which a wafer cassette isintroduced, a control panel 202 for controlling a loading/unloadingstation and a plating bath station, a signal tower 203, and a electricbox 204 electrically connected to the control panel 202.

[0074] In FIG. 13, the electroplating system includes aloading/unloading station 210 and a plating bath station 240. In theloading/unloading station 210, a wafer is removed from a wafer cassetteand thereafter, removably mounted to the wafer holder. Also, the waferis removed from the wafer holder and thereafter, loaded within the wafercassette. The wafer holder of the present invention enables the use ofthe loading/unloading station 210. In the bath station 240, the waferholder is immersed in an electrolytic solution within a plating bath forelectroplating of the semiconductor wafer.

[0075] Again, an electroplating system according to a third aspect ofthe invention provides a loading/unloading station whereby a wafer istransferred from a wafer cassette to the wafer holder, and the wafer istransferred from the wafer holder to the wafer cassette, and a platingbath station wherein the wafer is plated while the wafer holder isimmersed in an electrolytic solution within a plating bath.

[0076] The loading/unloading station 210 includes, among others, acassette table 212 on which a wafer cassette is placed, a wafer transferrobot 216, a wafer centering device 218, and a spin dryer 219.Preferably, the cassette table 212 includes a sensor unit 214 fordetecting the existence of a wafer within a wafer cassette. The sensorunit 214 includes a sensor for detecting as to whether or not a wafer ismounted in a given position within a wafer cassette, and a drive formoving the sensor. The sensor is typically moved in a verticaldirection. The wafer transfer robot 216 is capable of removing a waferfrom a wafer cassette and transferring the wafer to a holder clamp. Thewafer transfer robot 216 is also capable of unloading the wafer from theholder clamp and transferring the wafer to the wafer cassette. The wafertransfer robot 216 is preferably moved for rotation. The spin dryer 219is design to dry a semiconductor wafer after it has been plated.

[0077] The loading/unloading station 210 includes one or more tables 220with wafer loading/unloading tables 222 a, 222 b. The waferloading/unloading table 222 a is moved to and away from the waferloading/unloading table 222 b, and vice versa. A holder clamp is mountedto the upper part of the wafer loading/unloading table 222 b.One form ofthe holder clamp is shown in FIGS. 14A and 14B. The loading/unloadingstation preferably includes a means (not shown) for detecting as towhether or not a wafer is electrically connected to the wafer holder.

[0078] The electroplating system 200 includes a holder container 230within which holders 232 are contained. In the embodiment shown in FIG.13, the holder container 230 includes upper and lower sections, withthirteen holders being contained in each section. The holder container230 preferably includes a sensor for detecting the existence of aholder.

[0079] The bath station 240 includes, among others, a plating bath 250,a cleaning bath 260 and a dryer 270. The plating bath 250 preferablyincludes a plurality of compartments 252. In each compartment, oneholder within which a wafer is loaded is immersed in an electrolyticsolution for plating. Preferably, each compartment includes a portioninto which a holder is introduced, a unit for supplying electricalcurrent to the holder, and an anode. An exposed surface of the anodewhich is oriented to face with a wafer is preferably concentric with thewafer. A plurality of compartments may be agitated by a single agitator258. For example, an agitator rod may be moved in a direction parallelto the surface of a wafer to agitate two compartments. The agitator rodmay have variable speeds.

[0080] In the cleaning bath 260, it is preferable that pure water iscaused to flow upwardly from its bottom so as to clean the holder and aplated surface of the wafer within the holder. It is also preferablethat the holder is quickly dumped into the cleaning bath so as toimprove the cleaning result.

[0081] It is preferable to use the dryer 270 to dry the holder and awafer loaded within the holder. A suitable gas 5 may be brown to removewater droplets from the holder and the wafer.

[0082] Thereafter, the holder is transferred to the holderloading/unloading tables 222 a, 222 b. The wafer is removed from theholder and then, loaded within the wafer cassette.

[0083] The holder transfer robot is moved along a travel of path 280 soas to move the holder between the loading/unloading station 210 and theplating bath station 240.

[0084] A HEPA filter is preferably attached to the ceiling 5 (not shown)of the loading/unloading station 210 to cause fresh air to flowdownwardly from the ceiling. This prevents the flow of steam from theplating bath 250 to the loading/unloading station 210.

[0085] In the event of a failure, it is preferable to first develop analarm signal and give an indication to that effect and then,automatically stop the electroplating system.

[0086] Operation of the electroplating system is as follows. First, awafer is removed from the wafer cassette. The wafer is then loaded intothe wafer holder. These steps thus include removal of wafer from thewafer cassette and transfer of the holder 232 from the holder container230 to the wafer loading/unloading table 222 b.

[0087] More specifically, the wafer cassette is placed at a givenlocation in the loading/unloading station. The start button is thenpressed to cause a holder transfer robot (not shown) to move the holder232 out of the holder container 230. The holder is then placed on thewafer loading/unloading table 222 b. The wafer transfer robot 216 isoperable to move a wafer out of the wafer cassette. The wafer is thenplaced on the wafer loading/unloading table 222 b.

[0088] The holder clamp is then operable to load the wafer into theholder on the wafer loading/unloading table 222 b. The waferloading/unloading table 222 b is thereafter moved to an area where thewafer loading/unloading station 222 a is located. The holder transferrobot (not shown) is operable to transfer the holder together with awafer from the wafer loading/unloading table 222 a to a compartment 252in the plating bath 250. Electrical current is then supplied for apredetermined period of time so as to plate the wafer.

[0089] When the wafer has been plated, the holder transfer robot isoperable to transfer the holder to the cleaning bath 260. After thewafer is cleaned, a gas is blown from the dryer 270 to remove waterdroplets from the wafer.

[0090] The holder transfer robot is again operable to transfer theholder to the holder clamp. The wafer is, then, unloaded from theholder. The wafer is, thereafter, introduced into a spin dryer 219. Onthe other hand, the holder is transferred to the holder container 230.The wafer is rinsed while it is rotated within the dryer. The wafer is,thereafter, rotated at a high speed to finalize the drying process.After the wafer has been dried, the wafer is returned to the wafercassette within which the wafer is originally loaded. When all thewafers are completely processed, a buzzing sound is produced, and thesystem is in a standby position.

[0091]FIG. 14A shows one form of the holder clamp. Specifically, aholder clamp 300 includes a drive, not shown, a rotary shaft 302 capableof reciprocation along its own axis and rotation about its own axis, acircular disk 304 mounted on the shaft 302, and a circular disk 306fixed to the circular disk 304. The circular disk 306 includes a meansfor detachable engagement with the wafer holder. Illustratively, such ameans includes a plurality of pins 310 a, 310 b.

[0092] As shown in FIG. 14B, a wafer holder 320 includes holes 322 a,322 b. The pins 310 a, 310 b are inserted into these holes 322 a, 322 b,respectively when the drive causes downward movement of the shaft 302.When the shaft is rotated in a clockwise or counterclockwise directionby a fixed angle, the pins 310 a, 310 b cause the wafer holder 320 torotate by a fixed angle. This rotation allows the wafer holder 320 toclamp or fasten a semiconductor wafer loaded in the wafer holder.Thereafter, the shaft 302 is lifted to disengage the pins 310 a, 310 bfrom the wafer holder.

[0093] In the embodiment shown in FIG. 8, for example, when the holderclamp 300 is lowered, the pins 310 a, 310 b are inserted into thegrooves where the ring retainers 119 are disposed. When the pins 310 a,310 b are rotated by a fixed angle, the ring clamp 119 is rotated toclamp the ring clamp 114 and thus, the semiconductor wafer.

[0094] Reverse operation causes the ring clamp 114 of the wafer holder320 to rotate in an opposite direction. This rotation loosens the ringclamp 114.

[0095] The present invention provides the following advantageouseffects.

[0096] In one aspect of the present invention, the semiconductor wafer16 can readily be mounted or loaded.

[0097] The packing has an inverted U-shape with opposite end projectionsplaced in contact with the first holding member and the semiconductorwafer, respectively. The end projections collectively define a holewithin which the second conductive element is received. The secondconductive element is mounted to the second holding member through aresilient material. This arrangement provides a simple wafer holder withits electrical contact reliably sealed by the packing.

[0098] The second conductive element has an inverted U-shape sectionwith opposite end projections bridging between the first conductiveelement of the first holding member and the conductive layer of thesemiconductor wafer. The second conductive element is mounted to thesecond holding member through a resilient material. This arrangementensures supply of electrical current to the conductive layer of thesemiconductor wafer.

[0099] In another aspect of the present invention, the ring clamp isemployed to press the second holding member against the first holdingmember. This arrangement enables uniform application of pressure ontothe packing and provides a better seal.

[0100] The use of the inverted L-shaped pawls makes it easy to seal therequired part.

[0101] Additionally, the use of the hinge mechanism facilitatespositioning between the first and second holding members.

[0102] Finally, the ring clamp is capable of rotation on the secondholding member by a given angle. This configuration allows for readypositioning of the ring clamp relative to the pawls.

What is claimed is:
 1. A semiconductor wafer holder comprising: a firstholding member having a semiconductor wafer support surface; an annularsecond holding member; a ring clamp rotatable relative to said secondholding member to thereby urge said second holding member towards saidfirst holding member so as to hold a semiconductor wafer therebetween,said second holding member being provided with a packing that has acontact surface adapted to be brought into contact with said firstholding member in a sealing fashion when said first and second holdingmembers hold therebetween the semiconductor wafer, said packing having arecess formed in said contact surface; and a conductive member providedin the recess of said packing and placed in contact with a conductivelayer of the semiconductor wafer when said first and second holdingmembers hold therebetween the semiconductor wafer.
 2. A semiconductorwafer holder as set forth in claim 1, further comprising a memberresiliently pressing said conductive member against the conductive layerof the semiconductor wafer.
 3. A semiconductor wafer holder as set forthin claim 1, wherein said first holding member is plate-shaped.
 4. Asemiconductor wafer holder according to claim 1, wherein said ring clamphas an outer periphery having a plurality of protrusions formed thereon,said protrusions being arranged at given intervals, and said firstholding member includes a plurality of pawls of an inverted L-shape,said plurality of protrusions being slid below said plurality of pawlsto thereby clamp said first and second holding members together whensaid clamp is rotated through a given angle.
 5. A semiconductor waferholding according to claim 1, further comprising a hinge mechanism bywhich said first holding member and said second holding member areconnected, said first and second holding members being pivotable aboutsaid hinge mechanism.
 6. A semiconductor wafer holding according toclaim 1, further comprising a ring retainer by which said second holdingmember and said ring clamp are connected, said ring clamp being capableof rotation on said second holding member through a specified angle. 7.A semiconductor wafer holder comprising: a first holding member in theform of a plate; an annular second holding member including a packingmounted thereon; and a ring clamp operable to press said second holdingmember against said first holding member so as to hold a semiconductorwafer therebetween, the semiconductor wafer having an outer periphery,said first holding member including a first conductive element arrangedadjacent to the outer periphery of the semiconductor wafer held betweensaid first and second holding members, and said packing of said secondholding member including a second conductive element which is placed incontact with said first conductive element and the conductive layer ofthe semiconductor wafer when the semiconductor wafer is held betweensaid first and second holding members and sealed by said packing.
 8. Asemiconductor wafer holder according to claim 7, wherein said ring clamphas an outer periphery having a plurality of protrusions formed thereon,said protrusions being arranged at given intervals, and said firstholding member includes a plurality of pawls of an inverted L-shape,said plurality of protrusions being slid below said plurality of pawlsto thereby clamp said first and second holding members together whensaid clamp is rotated through a given angle.
 9. A semiconductor waferholding according to claim 8, further comprising a hinge mechanism bywhich said first holding member and said second holding member areconnected, said first and second holding members being pivotable aboutsaid hinge mechanism.
 10. A semiconductor wafer holding according toclaim 7, further comprising a hinge mechanism by which said firstholding member and said second holding member are connected, said firstand second holding members being pivotable about said hinge mechanism.11. A semiconductor wafer holding according to claim 10, furthercomprising a ring retainer by which said second holding member and saidring clamp are connected, said ring clamp being capable of rotation onsaid second holding member through a specified angle.
 12. Asemiconductor wafer holding according to claim 7, further comprising aring retainer by which said second holding member and said ring clampare connected, said ring clamp being capable of rotation on said secondholding member through a specified angle.
 13. A semiconductor waferholder for use in an electroplating system, the semiconductor waferholder comprising: an annular insulative member defining a centralopening; an annular packing disposed on said annular insulating memberand defining a contacting surface for contacting a semiconductor wafer;and at least one conductive member serving as a cathode and defining aportion of said contacting surface; wherein said annular packing has aninner portion disposed diametrically interior to said at least oneconductive member and an outer portion disposed diametrically exteriorto said at least one conductive member.
 14. A semiconductor wafer holderaccording to claim 13, wherein said at least one conductive membercomprises one or more connectors having a plurality of holes.
 15. Asemiconductor wafer holder according to claim 13, wherein said annularinsulative member comprises an insulating material.
 16. A semiconductorwafer holder according to claim 15, wherein said insulating materialcomprises synthetic resin.
 17. A semiconductor wafer holder according toclaim 13, wherein said annular packing is removable.
 18. A semiconductorwafer holder according to claim 13, wherein said annular packingcomprises an elastic material.
 19. A semiconductor wafer holderaccording to claim 13, wherein said at least one conductive member isconnected to an external electrode.
 20. A semiconductor wafer holderaccording to claim 13, wherein said annular packing and said at leastone conductive member comprise a monolithic piece.
 21. A semiconductorwafer holder according to claim 13, further comprising a plate-likeholding member for holding the semiconductor wafer together with saidannular insulative member.
 22. A semiconductor wafer holder according toclaim 21, wherein said plate-like holding member comprises an insulativematerial.
 23. A semiconductor wafer holder for use in an electroplatingsystem, the semiconductor wafer holder comprising: an annular insulativemember defining a central opening; an annular packing disposed on saidannular insulating member and defining a contacting surface forcontacting a semiconductor wafer; and at least one conductive memberserving as a cathode and defining a portion of said contacting surface;wherein said at least one conductive member is connected to a connectordisposed through said annular insulative member, and said connector isadapted to be connected to an external electrode.
 24. A semiconductorwafer holder according to claim 23, wherein said annular insulativemember comprises an insulating material.
 25. A semiconductor waferholder according to claim 24, wherein said insulating material comprisessynthetic resin.
 26. A semiconductor wafer holder according to claim 23,wherein said annular packing is removable.
 27. A semiconductor waferholder according to claim 23, wherein said annular packing comprises anelastic material.
 28. A semiconductor wafer holder according to claim23, wherein said at least one conductive member is connected to anexternal electrode.
 29. A semiconductor wafer holder according to claim23, wherein said annular packing and said at least one conductive membercomprise a monolithic piece.
 30. A semiconductor wafer holder accordingto claim 23, further comprising a plate-like holding member for holdingthe semiconductor wafer together with said annular insulative member.31. A semiconductor wafer holder according to claim 30, wherein saidplate-like holding member comprises an insulative material.
 32. Asemiconductor wafer holder for use in an electroplating system, thesemiconductor wafer holder comprising: an annular insulative memberdefining a central opening; an annular packing disposed on said annularinsulating member and defining a contacting surface for contacting asemiconductor wafer; and a plurality of conductive members disposed insaid annular insulating member, each of said conductive members havingan inner portion which contacts a semiconductor wafer and serves as acathode, and an outer portion which is adapted to contact a conductiveelement electrically connected to an external electrode.
 33. Asemiconductor wafer holder according to claim 32, wherein saidconductive member comprises one or more connectors having a plurality ofholes.
 34. A semiconductor wafer holder according to claim 32, whereinsaid annular insulative member comprises an insulating material.
 35. Asemiconductor wafer holder according to claim 34, wherein saidinsulating material comprises synthetic resin.
 36. A semiconductor waferholder according to claim 32, wherein said annular packing is removable.37. A semiconductor wafer holder according to claim 32, wherein saidannular packing comprises an elastic material.
 38. A semiconductor waferholder according to claim 32, wherein said annular packing and said atleast one conductive member comprise a monolithic piece.
 39. Asemiconductor wafer holder according to claim 32, further comprising aplate-like holding member for holding the semiconductor wafer togetherwith said annular insulative member.
 40. A semiconductor wafer holderaccording to claim 39, wherein said plate-like holding member comprisesan insulative material.
 41. A semiconductor wafer holder according toclaim 32, wherein said conductive element is provided on said plate-likeholding member.
 42. An electroplating system for electroplating asemiconductor wafer, comprising: a plating bath containing anelectrolytic solution; an anode disposed within said plating bath; and asemiconductor wafer holder for holding the semiconductor wafer so as toallow the semiconductor wafer to face said anode, the semiconductorwafer holder comprising: an annular insulative member defining a centralopening; an annular packing disposed on said annular insulating memberand defining a contacting surface for contacting a semiconductor wafer;and at least one conductive member serving as a cathode and defining aportion of said contacting surface, wherein said annular packing has aninner portion disposed diametrically interior to said at least oneconductive member and an outer portion disposed diametrically exteriorto said at least one conductive member.
 43. An electroplating systemaccording to claim 42, wherein said at least one conductive membercomprises one or more connectors having a plurality of holes.
 44. Anelectroplating system according to claim 42, wherein said annularinsulative member comprises an insulating material.
 45. Anelectroplating system according to claim 44, wherein said insulatingmaterial comprises synthetic resin.
 46. An electroplating systemaccording to claim 42, wherein said annular packing is removable.
 47. Anelectroplating system according to claim 42, wherein said annularpacking comprises an elastic material.
 48. An electroplating systemaccording to claim 42, wherein said at least one conductive member isconnected to an external electrode.
 49. An electroplating systemaccording to claim 42, wherein said annular packing and said at leastone conductive member comprise a monolithic piece.
 50. An electroplatingsystem according to claim 42, further comprising a plate-like holdingmember for holding the semiconductor wafer together with said annularinsulative member.
 51. An electroplating system according to claim 50,wherein said plate-like holding member comprises an insulative material.52. An electroplating system for electroplating a semiconductor wafer,comprising: a plating bath containing an electrolytic solution; an anodedisposed within said plating bath; and a semiconductor wafer holder forholding the semiconductor wafer so as to allow the semiconductor waferto face said anode, the semiconductor wafer holder comprising: anannular insulative member defining a central opening; an annular packingdisposed on said annular insulating member and defining a contactingsurface for contacting a semiconductor wafer; and a plurality ofconductive members disposed in said annular insulating member, each ofsaid conductive members having an inner portion adapted to contact asemiconductor wafer and serving as a cathode, and an outer portionadapted to contact a conductive element electrically connected to anexternal electrode.
 53. An electroplating system according to claim 52,wherein said conductive member comprises one or more connectors having aplurality of holes.
 54. An electroplating system according to claim 52,wherein said annular insulative member comprises an insulating material.55. An electroplating system according to claim 54, wherein saidinsulating material comprises synthetic resin.
 56. An electroplatingsystem according to claim 52, wherein said annular packing is removable.57. An electroplating system according to claim 52, wherein said annularpacking comprises an elastic material.
 58. An electroplating systemaccording to claim 52, wherein said annular packing and said at leastone conductive member comprise a monolithic piece.
 59. An electroplatingsystem according to claim 52, further comprising a plate-like holdingmember for holding the semiconductor wafer together with said annularinsulative member.
 60. An electroplating system according to claim 59,wherein said plate-like holding member comprises an insulative material.61. An electroplating system according to claim 52, wherein saidconductive element is provided on said plate-like holding member.